This invention relates, in general, to locating and testing semiconductor devices, and more specifically to locating conductive features of a semiconductor device without the need for precise alignment.
Manufacturers of semiconductor devices, including devices formed as small semiconductor die, must test these devices for functionality and durability at the end of the manufacturing process. As electronic devices such as semiconductor die become smaller, they become more difficult to test. The difficulty is due in large part to the fact that as the devices become smaller the device terminals, such as pads or electrically conductive bumps on the underside of the die, become smaller and more closely spaced. Conventionally, in order to test such devices, a "bed-of-nails" tester configuration is employed. The bed-of-nails tester includes an array of tiny pins corresponding to the array of device terminals on the die. These tiny pins provide the test signals to the semiconductor device. Consequently, the pins of the bed-of-nails must be carefully and precisely aligned to correspond to the array of device terminals. Furthermore, the bed-of-nails type tester is inherently very delicate and prone to damage and misalignment.
Other test methods for testing semiconductor devices in the form of die (or a wafer full of die) include using an array of test terminals which provide the test signals, laid out on a flexible printed circuit membrane. Like the tiny pins in the bed-of-nails configuration, the test terminals laid out on the flexible printed circuit membrane must precisely match the terminals on the die in order to make contact to the device terminals during testing. Additionally, in both the bed-of-nails type system and the system with test terminals laid out on a printed circuit, the semiconductor device must be precisely aligned with the test fixture so that the device terminals touch the test terminals or pins.
The conventional methods described require extremely precise alignment between the device under tests and the test fixture, during testing. Furthermore, the conventional systems described tend to be extremely delicate and prone to damage and misalignment. Consequently, what is needed is a test system which can accurately bring test signals to the device terminals, irrespective of the alignment of the die and the test fixture. Furthermore, what is needed is a system which is robust, and not prone to misalignment or damage.